The UN agency for Palestinian refugees says new Israeli restrictions on Gaza will worsen living conditions there.
Agency spokesman Chris Gunness said Thursday it could have "profound and far-reaching consequences for already desperate civilians."
Gaza is home to nearly 2 million people, 80 percent of whom rely on humanitarian aid.
Israel this week shut the only cargo crossing with Gaza in response to incendiary kites and balloons sent across the frontier into Israel. It is still allowing food, medicine and humanitarian aid in through the crossing.
The kites are part of a campaign led by Gaza's Hamas rulers against a crippling blockade Israel and Egypt imposed when the terror organization seized control of the territory in 2007.